Although mucin glycoproteins are major functional constituents of the pre- ocular tear film, little is known about their molecular identity, synthesis or secretion. Molecular studies of human intestinal respiratory and mammary mucins have led to the identification and partial sequencing of eight distinct mucin species (MUCl-MUC8). Different mucosal tissues have unique protective requirements which are reflected by tissue specific differences in mucin expression and/or secretion. The overall goal of the proposed studies is to define the contribution of conjunctival mucins to the human tear film. The hypothesis to be investigated is that ocular mucins consist of several distinct gene products the secretion of which may be differentially regulated. We propose to use molecular biological, immunological, morphological and pharmacological approaches to investigate mucins gene expression and secretion in normal human conjunctiva. The Aims of this project are: 1. Identification of mucin gene products in human conjunctival tissue. 2. Localization of regional and cellular sites of conjunctival mucin gene expression. 3. Analysis of mucin composition and secretion in the preocular tear film. The proposed studies will be among the first, in any system, to explore the relationship between mucin gene expression and secretion. Investigation of biochemical pathways governing synthesis, storage and release of mucin may suggest novel molecular approaches to control of ocular mucin production.